Buckshot Racing #77 billet cylinder heads for Mercury 2.5L V6 two-strokes. Replaceable 26cc, 30cc, and 36cc combustion chambers, multiple gasket thicknesses, thermostat or restrictor provisions, water pressure and temperature ports, and factory-style head temperature sensor mounting.
The new Buckshot Racing #77 Billet Cylinder Heads for Mercury 2.5L V6 two-strokes are built around one goal: giving the engine builder more control over compression, combustion-chamber volume, cooling configuration and instrumentation without permanently modifying the main cylinder head.
Manufactured for Buckshot Racing #77 by OX Performance, the heads are machined from billet aluminum and feature replaceable combustion-chamber pockets in 26cc, 30cc and 36cc configurations. Combined with multiple head-gasket thicknesses, this gives builders a highly tunable platform for recreational performance, lake racing, drag racing and dedicated Mercury Racing applications.
Replaceable 26cc, 30cc & 36cc Combustion Chambers
The most important feature is the replaceable chamber-pocket design.
Instead of permanently fly-cutting or machining the head every time compression requirements change, the chamber pocket can be changed to suit the engine combination.
The 26cc chamber is intended for aggressive high-compression race setups where fuel octane, ignition timing and the rest of the engine package are configured for the added cylinder pressure.
The 30cc chamber provides a strong middle-ground performance option for modified Mercury 2.5L engines that need increased compression without moving to the smallest chamber.
The 36cc chamber provides a larger combustion volume for more conservative compression and broader fuel compatibility. This allows the same billet head body to be configured for very different Mercury 2.5L builds.
Tunable Head-Gasket Thickness
The Buckshot Racing #77 billet heads use a gasketed cylinder-head design, giving the builder another major tuning variable.
Available gasket thicknesses include: 0.75 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, and 1.5 mm. Head-gasket thickness changes the final chamber volume, piston-to-head clearance, and compression ratio. A thinner gasket generally reduces clearance and increases compression, while a thicker gasket increases clearance and lowers compression.
When the gasket thickness and replaceable chamber volume are selected together, the builder can fine-tune the engine for pump fuel, premium fuel, race fuel, high-compression lake use, or dedicated competition.
Built for Mercury 2.5L Performance Applications
These heads are intended for compatible Mercury and Mariner 2.5L V6 gasket-head two-strokes, including many performance and racing combinations based on engines such as the 150, 175 and 200 HP V6, XR6, XRi, Pro Max, 245 Carb, 260 EFI, 280 ROS, 300 Drag and S3000.
Because Mercury used different cooling and head configurations over the years, final fitment should always be confirmed by the block, gasket pattern, cooling configuration and engine setup, not horsepower alone.
Thermostat or Restrictor Washer Ready
The heads are designed to retain the original-style Mercury thermostat arrangement or allow the use of restrictor washers for race cooling systems.
That gives builders the ability to maintain a more conventional cooling strategy for recreational or performance use, or configure the engine for a race-style cooling system where restrictors are preferred.
This flexibility is especially useful when the same basic head package may be used on a lake engine, drag engine or tunnel-boat race motor.
Factory Head Temperature Sensor Provision
A dedicated location is built into the head for the factory Mercury cylinder-head temperature sensor. This allows the original head-temperature monitoring function to remain in place rather than forcing the builder to relocate or eliminate the sensor.
Keeping the factory-style temperature sensor provision is particularly valuable on engines where warning-system or temperature-monitoring functions are retained.
Water Pressure & Water Temperature Ports
The heads also incorporate dedicated provisions for water pressure and water temperature monitoring. Monitoring water pressure helps verify that the engine is receiving adequate cooling-water flow, especially on high-performance boats running elevated engine heights or modified cooling systems.
A dedicated water-temperature port gives the builder another way to monitor actual cooling-system performance during testing, tuning, and racing.
Together with the factory head-temperature sensor provision, the billet heads provide a much more complete instrumentation package than a basic replacement cylinder head.
Designed for Real Compression Tuning
The combination of 26cc, 30cc, and 36cc replaceable chambers with multiple gasket thicknesses gives the engine builder a wide range of possible compression configurations.
The correct setup should never be chosen from chamber volume alone.
Final compression depends on deck height, piston position at TDC, chamber volume, gasket thickness, gasket crush, previous block or head machining, fuel octane, and ignition timing.
For any serious performance build, actual piston-to-head clearance and cranking compression should be measured before the engine is operated under load.
Buckshot Racing #77 Mercury 2.5L Billet Head Features
The complete head system combines billet aluminum construction, replaceable 26cc / 30cc / 36cc combustion chambers, six gasket-thickness options, thermostat or restrictor compatibility, factory temperature-sensor mounting, water-pressure monitoring, and water-temperature monitoring.
For Mercury 2.5L builders working with BB, CC, EE, FF, Pro Max, XR6, 245 Carb, 260 EFI, 280 ROS, 300 Drag, S3000, and other high-performance V6 combinations, this creates a highly serviceable and tunable cylinder-head platform without locking the engine into one compression configuration.
Contact Mike Hill at +1-714-697-1716 for tech support.